Insecure update error - SUPublicDSAKeyFile

A minute ago I had the following popup appear:

Insecure update error!
For security reasons, the file (dsa_pub.pem) indicated by the 'SUPublicDSAKeyFile' key needs to exist in the bundle's Resources.

I have no idea what application generates this error. If I open up the Console and search for "SUPublicDSAKeyFile" or other strings, I don't find anything.

How can I find out what this is about?

The error comes from the Sparkle Update system (SU). It is a freely available system for integration by developers into apps to provide online updating of their apps.

The error message you see could come from any of your third party apps that are using Sparkle (it is very popular).

The error message indicates that an important file is missing from the application's bundle. This usually indicates developer error (i.e. the program you've downloaded was "flawed" to begin with) - or it could be caused by you manually deleting the file.

I would start with Activity Monitor to see which third party apps you're running, and simply try closing down app after app until you're left with the one responsible for this popup.

To see which app is using this library run this in terminal

find /Applications -name Sparkle.framework

the you will get something like:

/Applications/VLC.app/Contents/Frameworks/Sparkle.framework
/Applications/ForkLift.app/Contents/Frameworks/Sparkle.framework
/Applications/Docker.app/Contents/Frameworks/Sparkle.framework
/Applications/Wireshark.app/Contents/Frameworks/Sparkle.framework